This invention relates to compression testing of grout samples and, more particularly, to an unbonded capping system.
Grout is a material used in reinforced masonry construction. Particularly, grout is placed in the cells of hollow concrete masonry units, sometimes referred to as cinder blocks. The grout must be fluid so that it completely fills the cells to provide a solid, grouted masonry wall. To satisfy these requirements, the grout is more fluid than concrete or mortar. Particularly, concrete typically has a slump in the range of 2 inches to 6 inches. Mortar typically has a slump in the range of 5 inches to 8 inches. Grout typically has a slump in the range of 8 inches to 10 inches. This fluidity allows the grout to flow through the grout space, around reinforcing bars and completely surround and bond to steel and concrete masonry units.
Presently, grout samples are tested for compression as a verification of strength. The traditional method for forming three grout samples for testing is to configure twelve concrete masonry units to form three chambers in the form of rectangular prisms. The chambers are lined with filter paper or other paper product. The chambers are filled with grout which is allowed to harden. An alternative procedure for forming grout samples is a grout sample box 10, see FIG. 1, made of corrugated cardboard. The grout sample box includes a divider 12 that divides the box into four rectangular compartments 14. Each compartment 14 is filled with grout which then hardens to form samples 16 in the form of rectangular prisms. Particularly, each sample has generally square-shaped end walls 18. As is apparent, the particular size of the overall sample and each wall is dependent on the apparatus used for forming the grout sample.
Compression tests of the grout samples are performed by placing the sample between platens of a testing apparatus and the sample compressed until it fails. The platens are planar. Imperfections in the end walls can create pressure points that distort the compression tests. Current procedures require the grout samples to be capped with a sulfur compound to provide a smooth, hard surface which fills any imperfections which normally occur when making grout samples. Capping the grout sample using sulfur compound requires the sulfur to be heated, poured into a capping fixture, placed onto the grout sample and allowed to cool. This procedure requires considerable preparation time. Additionally, the heating of the sulfur compound not only gives off noxious odors but the vapors may combine with humidity in the air to create sulfuric acid. This acid is airborne and over time damages equipment and structures and, more importantly, can create a health hazard.
The present invention is directed to further improvements in grout sample compression testing.
In accordance with the invention, there is provided an unbonded capping system for compression testing of grout samples.
Broadly, in accordance with one aspect of the invention an unbonded capping system is provided for compression testing of grout samples in the form of rectangular prisms. The capping system comprises first and second retaining cups comprising metal blocks each having opposite parallel planar surfaces. A first of the planar surfaces is engagable by a test platen, in use. A second of the planar surfaces has a rectangular cavity for receiving one end of the grout sample. First and second rectangular compression pads each have a hardness in the range of about 50-70 durometer. The compression pads are of a size slightly smaller than a size of the rectangular cavities to be received therein to distribute a test load from the test platens to the grout sample.
In accordance with another aspect of the invention, the unbonded capping system comprises first and second rectangular elastomeric compression pads.
It is a feature of the invention that the compression pads may each have a hardness of about 50 durometer.
It is another feature of the invention that the first and second retaining cups may be of high alloy steel construction.
It is a further feature of the invention that the first and second retaining cups may be cylindrically shaped and the parallel planar surfaces define end walls.
It is yet another feature of the invention that the first and second rectangular compression pads may comprise neoprene pads.
It is yet a further feature of the invention that the rectangular cavities may comprise square cavities.
It is still a further feature of the invention that the rectangular cavity size may be larger than the size of an end face of the grout sample.
Further features and advantages of the invention will be readily apparent from the specification and from the drawings.